EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

The use of biomass in metallurgical coke production has been identified as one of the main possibilities to introduce a renewable carbon source to the process chain of blast furnace based steel production, thereby decreasing the CO2 emissions produced by the steel industry. In this study, multiple grades of bio-cokes are prepared by combining charcoal produced from pine chips at a high temperature (600 oC) with a high fluidity coking coal. The objective of this study is to investigate how the proportion of charcoal and the selected particle size of charcoal affect the strength and reactivity of bio-coke. The preparation of bio-cokes and reference cokes is performed in a laboratory-scale coking battery up to a final temperature of 1200 °C. The compressive strength of the coke grades is measured both at room temperature and at an elevated temperature simulating the lower blast furnace with a Gleeble 3800 thermomechanical simulator. Chemical reactivity of the coke grades is measured both in isothermal and dynamic conditions. The reactivity tests are performed in simulated blast furnace shaft conditions including all the relevant gases (CO, CO2, H2, H2O, N2) in realistic ratios. The results of this study provide new value to the current knowledge base of possible bio-coke utilization in the blast furnace, specifically on the effects of charcoal on cold and hot strength, chemical reactivity and the threshold temperature of coke gasification when the proportion of charcoal in the coking blend is in the range of 0–10 wt%.